Browsing by Author "Nunez, F."

Now showing 1 - 4 of 4
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    Fault detection and isolation in cooperative mobile robots using multilayer architecture and dynamic observers
    (CAMBRIDGE UNIV PRESS, 2011) Carrasco, R. A.; Nunez, F.; Cipriano, A.
    Mobile robot systems are being used more often in tasks that protect human operators from dangerous environments, but these benefits can be easily lost if the robots spend much of their time being repaired. This implies that any increment in their reliability will also improve their benefits. One way to achieve this is by adding redundant elements to the robot, but this adds complexity and cost to the design. On the other hand, cooperative mobile robots formed by members with the same basic structure provide a natural redundancy of elements, which may be used for reliability improvement. This work presents an architecture that takes advantage of the analytical and sensor redundancy present in groups of cooperative mobile robots in order to increase the reliability of the whole system. First, the design of the architecture is portrayed and the faults to be detected are described. The different layers of the system are then explained and analyzed using several simulations to test their capabilities and limitations. Finally, the experimental results on a group of small mobile robots are shown, validating the results delivered by simulations. These results show that the proposed architecture is able to detect and isolate correctly most of the faults tested.
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    Geographic latitude and sleep duration: A population-based survey from the Tropic of Capricorn to the Antarctic Circle
    (2017) Brockmann Veloso, Pablo Edmundo; Gozal, D.; Villarroel del Pino, Luis A.; Damiani Rebolledo, L. Felipe; Nunez, F.; Cajochen, C.
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    Metabolic consequences of snoring in adolescents and younger adults : a population study in Chile
    (2016) Brockmann Veloso, Pablo Edmundo; Damiani Rebolledo, L. Felipe; Smith, D.; Castet, A.; Nunez, F.; Villarroel del Pino, Luis A.; Gozal, D.
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    Short-term forecasting of electricity prices in the Colombian electricity market
    (INST ENGINEERING TECHNOLOGY-IET, 2009) Lira, F.; Munoz, C.; Nunez, F.; Cipriano, A.
    The restructuring of the electricity-generating industry from protected monopoly to an open competitive market has presented producers with a problem scheduling generation: finding the optimal bidding strategy to maximise their profits. In order to solve this scheduling problem, a reliable system capable of forecasting electricity prices is needed. This work evaluates the forecasting capabilities of several modelling techniques for the next-day-prices forecasting problem in the Colombian market, measured in USD/MWh. The models include exogenous variables such as reservoir levels and load demand. Results show that a segmentation of the prices into three intervals, based on load demand behaviour, contribute to an important standard deviation reduction. Regarding the models under analysis, Takagi-Sugeno-Kang models and ARMAX models identified by means of a Kalman filter perform the best forecasting, with an error rate below 6%.